A spontaneously occurring malignant pituicytoma in a male sprague dawley rat

Abstract

Pituicytoma is an extremely rare neoplasm derived from pituicytes, which are glial cells in the posterior lobe of the pituitary gland. A malignant pituicytoma was found in the intracranial cavity of a 55-week-old male Sprague-Dawley rat. Macroscopically, the tumor was located on the sphenoid bone and involved the pituitary gland. The tumor was composed of sheets of fusiform cells with spindle- or pleomorphic-shaped nuclei and abundant eosinophilic cytoplasms. The cells were arranged in a whirling or irregular growth pattern. Some tumor cells were bizarre multinucleated giant cells with cytoplasmic eosinophilic hyaline droplets. Many tumor cells were strongly positive for vimentin and glial fibrillary acidic protein, and some cells were positive for ED-1 and S-100. These findings closely resembled those of a giant cell glioblastoma derived from the pituitary gland, suggesting anaplastic pituicytoma. From our review of the literature, we believe this is the first report of a spontaneous malignant pituicytoma in a rodent.

Keywords: giant cells; glioblastoma; immunohistochemistry; pituicytoma; pituitary gland; rats.

Fig. 1.

(a) A gray-white mass was located on the sphenoid bone and involved the pituitary gland and trigeminal nerve. The solid line indicates the plane of section. (b) The bottom of the cerebrum was compressed and deformed by the intracranial mass. Scale: mm.

Fig. 2.

(a) The mass almost replaced the pituitary gland with invasion to the sphenoid bone (SB) but did not infiltrate the trigeminal nerves (TN) and tympanic cavities (TC) (×12.5). (b) Tumor cells invaded the sphenoid bone. (c) Tumor cells invaded the meninx of the cerebrum (MC) but not the parenchyma of the cerebrum (CB). (d) Small nests of native anterior cells were observed in the tumor (arrows) with congestion and thrombosis (*) (×100). Native anterior tissues were positive for CK (×200, inserted illustration). (e) The tumor was composed of sheets of fusiform cells with spindle- or pleomorphic-shaped nuclei and abundant eosinophilic cytoplasms. Many mitotic figures were seen in the tumor cells (arrows) (×400). (f) Bizarre multinucleated giant cells with eosinophilic hyaline droplets were observed (arrow) (×400). H&E staining.

Fig. 3.

Special staining for multinucleated giant cells with EHDs. EHDs were positive for PAS, deep purple after PTAH and brightly red after MT staining (arrows).

Fig. 4.

Immunohistochemical staining of tumor cells. The cytoplasms of the tumor cells were strongly immunoreactive for vimentin and GFAP. Some tumor cell nuclei were positive for S-100, and the existing nerve tissue was strongly positive for S-100. The cytoplasm of some tumor cells was immunoreactive for ED-1(×100). Many multinucleated giant cells (inserts) were also positive for vimentin and GFAP, and some of them had nuclei that were weakly positive for S-100. However, no cells were positive for ED-1 (arrows) (×400, enlarged illustration).